High sulfur fuel pellet with reduced so2 emission

ABSTRACT

The present description relates to a method and system for generating a fuel from high sulfur fuel waste materials having a reduced SO2 emission. In one example, the fuel may include petroleum coke, a biomass constituent, and an alkali substituent. Further in another example, the fuel may include iron oxide catalyst increasing the capture of SO2.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/216,772, entitled “HIGH SULFUR FUEL PELLET WITH REDUCED SO2EMISSION,” filed Mar. 17, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/526,301, entitled “HIGH SULFUR FUEL PELLET WITHREDUCED SO2 EMISSION,” filed on Jun. 18, 2012, which is acontinuation-in-part of U.S. application Ser. No. 13/415,631, “HIGHSULFUR FUEL PELLET WITH REDUCED SO2 EMISSION,” filed on Mar. 8, 2012,the entire contents of each are incorporated herein by reference for allpurposes.

FIELD

The present description relates to a method and system for a fuel pelletfrom high sulfur fuel waste materials having a reduced SO2 emission.

BACKGROUND AND SUMMARY

The emission of sulfur dioxide (SO2) from sulfur bearing fuels has beenrecognized as an environmental problem for many decades. Regulationshave been implemented to attempt to reduce the emission of SO2. It isknown that SO2 is a major air pollutant and has significant impacts uponhuman and animal health. In addition high concentrations of SO2 in theatmosphere can influence the habitat suitability for plant communities.Further, SO2 emissions are a precursor to acid rain and atmosphericparticulates.

Historically, burning coal and fuel oil used in power boilers resultedin a high level release of SO2. In recent years, petroleum coke hasbecome an alternative fuel. Petroleum coke (a waste product from crudeoil) is typically derived from coking heavy oil at many oil refineries.Petroleum coke has high sulfur content which when burned has high SO2emissions. If the crude oil is sour, the resulting coke will have highsulfur content.

Approximately over 50% of the current U.S. power supply comes from coalfired power plants. The fuel is selected on a balance of BTU value andsulfur content. All new plants built since 2005 must conform tostringent SO2 emission controls. The consequence is the necessity toinstall fuel gas desulfurization (FGD) systems. These desulfurizationsystems are methods of contacting the flue gas laden SO2 with alkalisorbents. The alkali sorbents may be limestone, lime and sodium basealkali. The sorbents can be applied as slurries or dry powders. In someuses, the flue gas is placed in contact with the sorbents to achieve thelongest contact and at the temperature most favorable to the alkali toacid reaction. The most favorable temperature range is frequentlyestimated as 750 C to 1100 C. The most efficient capture of SO2 isstated to be in a range of 900 C to 1100 C. There has been muchexperimentation in determining the effect of the surface area of thealkalis with efficiency of SO2 capture. The high temperatures needed toensure capture result in loss of generation capacity and/or increasedenergy consumption.

The costs of attempting to capture the SO2 with current systems arehigh. For example, the capital, operating and maintenance cost per shortton of SO2 removed (in 2001 US dollars) are highest for wet scrubbers(largest percentage of FGD scrubbers). For wet scrubbers larger than 400MW, the cost is $200 to $500 per ton. For wet scrubbers smaller than 400MW, the cost is $500 to $5,000 per ton. Similarly with spray dryscrubbers larger than 200 MW, the cost is $150 to $300 per ton and forspray dry scrubbers smaller than 200 MW, the cost is $500 to $4000 perton.

For small boilers, such as hog fuel boilers, the capital cost andmaintenance of these wet scrubber systems are prohibitive. Injectingsorbent into flue gas passing through spray towers or contact beds haveplugging problems that are inherent to the system.

Due to the high costs of remediation, another option that is currentlyused is to transport the high-sulfur fuel to a waste destination whereregulations may be less stringent. However, although it may be possibleto ship the high sulfur fuel (waste product) to a waste destination, theburning at the waste destination results in a release of SO2 (althoughin a different location). Moreover, waste product which is simply storedhas further negative environmental effects. Likewise, transport impactsin moving the waste fuel, including rail and shipping impacts, havenegative environmental effects.

The inventors herein have recognized the above-mentioned disadvantagesand have developed apparatus and methods for producing a manufacturedfuel pellet made from high sulfur carbonaceous compounds which emits areduced level of SO2 upon burning. In some example embodiments,petroleum coke is included in a fuel composition that utilizes the highcarbon content of the coke, a biomass constituent that provides thevolatiles to make the volatile deficient coke more ignitable and analkali constituent to capture the SO2 produced by burning high sulfurcoke. In other examples, a catalyst, such as an iron oxide catalyst mayfurther be added to increase the capture of SO2. The fuel compositionmay be formed as pellets, powders, briquettes, beads or any otheragglomerates.

The present embodiments disclosed herein may provide several advantages.Specifically, the approach may reduce the level of released SO2. Inaddition, the approach utilizes waste materials which previouslyrequired storage, transportation or alternative processing. By providingthe herein disclosed high sulfur fuel pellet with reduced SO2 emissions,environmental impact of the waste product can be reduced while stillutilizing the fuel properties of the product.

The above advantages and other advantages, and features of the presentdescription will be readily apparent from the following DetailedDescription when taken alone or in connection with the accompanyingdrawings.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic drawing depicting components for an examplepetroleum coke-based fuel.

FIG. 2 shows a process flow depicting an embodiment of a method forproducing a petroleum coke-based fuel.

FIG. 3 shows a schematic drawing depicting components for anotherexample petroleum coke-based fuel comprising an iron oxide catalyst.

DETAILED DESCRIPTION

The present description is related to systems and methods for generatingfuel pellets from a high sulfur waste product where the fuel pelletshave a reduced level of SO2 emission. In one non-limiting example, thefuel pellets may be configured as illustrated in FIG. 1. The method ofFIG. 2 may be executed to generate the petroleum coke based fuel shownin FIG. 1.

Fuels, such as coal and fuel oil, may be utilized for electricity and/orheat generation due to high energy density. Increasingly, petroleumcoke, which results from coking heavy oil at oil refineries, has beenidentified as an alternative fuel source due to its high carbon contentand nature as an industrial byproduct/waste product. However, thecombustion of petroleum coke may result in an unsafe level of SO2emissions. Once released into the atmosphere, SO2 can further oxidize tofor H2S04, thus forming acid rain. SO2 may further act as a precursor toincreased atmospheric particulate concentration. In response,regulations limiting SO2 emissions exist throughout the world.

Typically, flue gas resulting from the combustion of high-sulfurmaterials may be treated using one or more remediation mechanisms. Suchmechanisms may include, for example, Fuel Gas Desulfurization “FGD”systems configured to bring the flue gas in contact with wet (e.g.,slurry) or dry (e.g., powdered) alkali sorbents (e.g., limestone, lime,sodium-based alkali). Dry systems may require high temperatures. Othersystems may require long exposure times to ensure enough SO2 has beencaptured. The high temperature requirements result in decreasinggeneration capacity and/or increasing energy consumption. It is notedthat wet scrubbers may be near 100 C. Furthermore, such systems mayrequire additional maintenance to maintain efficiency. For example,systems configured to spray a sorbent slurry may require frequent nozzleclean-outs, thus increasing cost and downtime.

Furthermore, remediation mechanisms may have a greater impact on smallergeneration plants (e.g., smaller than 400 MW) such that remediation maycost an order of magnitude greater versus a larger generation plant. Asnoted above and as an example, remediation at a plant smaller than 400MW may cost $500 to $5000 per ton of SO2 removed, while remediation at aplant larger than 400 MW may cost $200 to $500 per ton of SO2 removed.

Regardless of generation capacity, as mentioned above, it may be moreeconomically feasible to transport high-sulfur fuel from areas with morestringent regulations to areas with looser regulations rather than or incombination with installing one or more remediation mechanisms. Suchtransport activities may result in a greater environmental impact due toboth the burning of high-sulfur fuels and the transport of such fuels tothe waste destination.

Accordingly, as described in more detail herein, a fuel pelletcomprising a high-sulfur carbonaceous compound is disclosed such thatthe burning of said fuel pellet may result in acceptable (e.g., belowregulated limit) SO2 emissions without utilizing independent SO2remediation systems, such as FGD. The disclosed systems and methods thusenable use of a waste product, high sulfur fuel, into a usable productsubstantially reducing the SO2 emissions of the waste product.

While the present disclosure is directed towards fuel pellets, it willbe understood that the fuel discussed herein may comprise any suitableform. Other example forms include, but are not limited to, powder,briquettes, beads and/or various agglomerates. In some examples,non-powdered forms may be utilized to avoid product loss, potentialhealth impact, and/or environmental impact due to increased dustconcentration in a powdered form. Powdered forms may further requireadditional consideration during transport and/or storage.

FIG. 1 shows a schematic drawing depicting components for a petroleumcoke-based fuel 100. Fuel 100 comprises petroleum coke 102, a biomassconstituent 104, and an alkali constituent 106. Additional additives maybe included in fuel 100 without departing from the scope of thedisclosure.

As previously mentioned, petroleum coke 102 is a byproduct/waste productof crude oil refining comprising a high carbon and sulfur content.Petroleum coke may be attractive as an energy source since typicalenergy density may be approximately 15,000-16,000 BTU per pound.

While the high carbon content of petroleum coke 102 may be desirable forits energy content, the sulfur content may lead to excessive SO2emissions. For example, petroleum coke may comprise approximately 3.2%sulfur. However, emissions regulations in the United States may limitsulfur emission to less than 2%. Thus, the petroleum coke, althoughhaving a substantial energy density in regards to use as a fuel, isconsidered a waste product due to the level of sulfur and the resultingSO2 emissions when burned.

In the present disclosure, petroleum coke may be combined with a biomassconstituent and an alkali constituent. In one example, alkaliconstituent 106 may comprise one or more compounds selected to capturethe SO2 produced during combustion of fuel 100. For example, Alkaliconstituent 106 may be selected at least in part based on its surfacearea, as increased surface area may increase the amount of SO2 capturedby alkali constituent 106. In some embodiments, alkali constituent 106may be further processed (e.g., by grinding) to increase surface area.

Alkali constituents 106 may comprise, for example, lime and calciumacetates. In some embodiments, alkali constituents 106 may be furtherprocessed to augment performance.

The alkali constituent may also be referred to herein as an SO2 sorbent.These SO2 sorbents may have enhanced reactivity compared to commerciallyavailable alkalis. As a non-limiting example, the SO2 sorbents may beenhanced by selecting the most reactive CaO and slaking it in reactionsthat provide Ca(OH)2 with the most surface area. Further, as anotherexample, one or more surfactants may be incorporated into the limepreparation process in order to increase SO2 capture efficiency ofalkali constituents 106.

It should be noted that the selection of the particle size of thepetroleum coke may affect the efficiency of the SO2 capture. It is notedthat in some examples (not as a limitation) capture of sulfur may be inthe range of 64% to 75%.

Further combined, in some examples, with the coke and the alkaliconstituent, is biomass constituent 104. Biomass constituent 104 mayprovide volatiles not present or are deficient in petroleum coke 102.Such volatiles may be selected as to increase the combustibility of thepetroleum coke 102. Biomass constituent 104 may comprise, for example,wood waste which, like petroleum coke 102, may be a byproduct/wasteproduct of one or more industrial processes.

It should be appreciated that the biomass constituent may be the woodwaste (1500 Kcal/Kg natural state; 3500 Kcal/Kg dry state approx.heating value) described above or may be other biomass products, wasteproducts or other combinations of such products. For example, thebiomass constituents may be, or may be combinations, of other animal andplant biproducts, including, but not limited to animal dung, such ascattle dung (1000 Kcal/Kg natural state; 3700 Kcal/Kg dry state approx.heating value), bagasse (2200 Kcal/Kg natural state; 4400 Kcal/Kg drystate approx. heating value), wheat and rice straw (2400 Kcal/Kg naturalstate; 2500 Kcal/Kg dry state approx. heating value), cane trash, ricehusk, leaves and vegetable wastes (3000 Kcal/Kg natural state; 3000Kcal/Kg dry state approx. heating value), coconut husks, dry grass andcrop residues (3500 Kcal/Kg natural state; 3500 Kcal/Kg dry stateapprox. heating value), groundnut shells (4000 Kcal/Kg natural state;4000 Kcal/Kg dry state approx. heating value), coffee and oil palm husks(4200 Kcal/Kg natural state; 4200 Kcal/Kg dry state approx. heatingvalue), cotton husks (4400 Kcal/Kg natural state; 4400 Kcal/Kg dry stateapprox. heating value), peat (6500 Kcal/Kg natural state; 6500 Kcal/Kgdry state approx. heating value), etc.

As a non-limiting example, a high sulfur fuel pellet with reduced SO2emissions may include a combination of high sulfur petroleum coke, abiomass constituent and an alkali constituent. A bituminous emulsion mayfurther make the pellets waterproof. As one example, the biomassconstituent may have enhanced reactivity by using the reactive CaO andslaking it in reactions that provide Ca(OH)2 with the most surface area.Selected particle sizes for the pet coke may increase the efficiency ofSO2 capture. Further, the lime SO2 capture efficiency may be increasedby incorporating surfactants in the lime preparation process. Such afuel pellet may capture SO2 at temperatures as low as 750 C and avoidthe necessity of FGD systems to handle high sulfur petroleum coke fuel.

As an example, a fuel pellet may include a biomass constituent in therange of approximately 10 to 50 percent by weight of the total mixtureof the fuel pellet. The alkali constituent may be in the range ofapproximately 1 to 30 percent by weight of the total mixture of the fuelpellet. The petroleum coke may fall in the range of 5 to 95 percent byweight but should be balanced with other constituents to provide a fuelpellet with acceptable volatile, BTU and SO2 levels in any particularuse as a fuel. As one example, and not as a limitation, the petroleumcoke may be approximately 65% by weight of the fuel pellet, the biomassconstituent may be approximately 30% by weight of the fuel pellet andthe alkali constituent may be approximately 5% by weight of the fuelpellet.

FIG. 2 shows a process flow depicting an embodiment of a method 200 forproducing a petroleum coke-based fuel. Method 200 comprises, at 202,processing petroleum coke. Typically, petroleum coke is supplied fromrefineries in granule form. Accordingly, processing the petroleum cokemay comprise one or more processes (e.g., grinding) configured toproduce a substantially powdered form of petroleum coke. A finelypowdered petroleum may be used in some examples as an increased surfacearea may result in increased combustibility. In other embodiments, thepetroleum coke may be supplied in a suitably powdered form.

It should be appreciated that in some embodiments, the pellets may be ofa select hardness to maintain form regardless of environmentalconditions, storage conditions, etc.

At 204, method 200 comprises processing a biomass constituent (e.g.,biomass constituent 104 of FIG. 1). For example, the biomass constituentmay comprise byproducts/waste products from a sawmill or other woodprocessor. Accordingly, similar to the processing of the petroleum coke,processing the biomass constituent may comprise one or more processes(e.g., grinding) configured to produce a substantially powdered form ofthe biomass constituent. A fine powder may be used in some examples, asthe increased surface area may increase the combustibility of theoverall fuel mixture. The biomass should not be construed as limited towood waste. It can also include paper of any type as well as cardboard,etc. The biomass can also include agricultural waste such as straw fromcrops, corn stalks or other plant stems. Even corn could be consideredas it is for fuel in stoves. In selecting any biomass, for inclusion inthe pellet mix, the volatiles content and BTU values must be consideredin making a balanced fuel pellet. Further, waste materials may beutilized. Moreover cost efficiency may also be a consideration inselecting a biomass.

At 206, method 200 comprises processing the alkali. As described abovein reference to FIG. 1, alkali (e.g., alkali constituent 106) maycomprise one or more compounds selected to capture the SO2 producedduring combustion of the fuel mixture. Since increasing surface area ofthe alkali constituent may increase the efficiency of SO2 capture,processing may comprise one or more processes (e.g., grinding)configured to produce an alkali with increased surface area.Furthermore, processing may involve incorporating surfactants into thelime preparation process in order to increase SO2 capture rate. It willbe understood that in some embodiments, alkali may be supplied in asuitable form such that no further processing occurs.

At 208, method 200 comprises combining the petroleum coke (e.g.,petroleum coke 102 of FIG. 1), biomass constituent (e.g., biomassconstituent 104 of FIG. 1), and additives (e.g., alkali sorbent 106 ofFIG. 1, and/or other additives) to produce a fuel mixture. Combining maycomprise one or more processes (e.g., mixing, heating, stifling, etc.)configured to produce a fuel mixture of the present disclosure (e.g.,fuel mixture 100 of FIG. 1).

At 210, method 200 comprises forming the fuel mixture into pellets. Asmentioned above, it will be understood that the fuel mixture may beprocessed into any number of suitable forms including, but not limitedto, briquettes, powders, beads and/or various agglomerates. Pellets asused herein include, but are not limited to, briquettes, powders, beadsand/or various agglomerates. Accordingly, forming the fuel mixture mayinclude one or more processes (e.g., molding, drying).

As will be appreciated by one of ordinary skill in the art, the methoddescribed in FIG. 2 may represent one or more of any number ofprocessing and manufacturing strategies. As such, various steps orfunctions illustrated may be performed in the sequence illustrated, inparallel, or in some cases omitted. Likewise, the order of processing isnot necessarily required to achieve the objects, features, andadvantages described herein, but is provided for ease of illustrationand description. Although not explicitly illustrated, one of ordinaryskill in the art will recognize that one or more of the illustratedsteps or functions may be repeatedly performed depending on theparticular strategy being used.

Powder River Basin sub bituminous “PRB” coal, including a similar energydensity is currently used by approximately 20% of coal-fired plants inthe United States. Accordingly, the disclosed fuel pellets may be easilyconsumed in these plants without significant adjustment to operatingparameters.

TABLE 1 Comparison between fuel pellets of the present disclosure andPRB coal. PRB Coal Fuel Pellets Carbon  70%  74% Hydrogen 4.6%  5.5%Sulfur 0.5% Up to 5.5% Nitrogen 0.93%  0.83% Oxygen 16.8%  0.94% Ash7.4% 16.8% BTU/lb 12,000 13,000 Volatiles 43%  42%

As illustrated in Table 1, the sulfur content of the resulting fuelpellet may be as high as 5.5%. However, due to the additional elementsof the fuel pellets (e.g., alkali sorbents), the resulting flue gas maycomprise a sulfur concentration comparable to the PRB Coal, which mayhave a sulfur content of 0.5%.

While the ash content of the fuel pellets is illustrated as being twicethat of PRB coal, it will be understood that the ash content isdependent upon the sulfur content of the petroleum coke. The remainingelements of the fuel pellets (i.e., alkali constituents and biomassconstituents) may be adjusted according to the petroleum cokecomposition. Accordingly, the ash content will be lower, and the BTUcontent will be higher, when a lower sulfur petroleum coke is used.

As examples to further illustrate the invention, pellet mixes aredescribed below. It should be appreciated that these examples areprovided for illustrative purposes only and not as a limitation.

In example one, the pellet mix dry basis was provided as follows:

Component Dry basis (pellet) Ash content Petroleum Coke  1249 g 2.50Wood Fiber 380  .76 Lime (Ca(OH)) 264 (200g CaO) 200    Asphalt 69 Total1962 g solids 203 g ash

The estimated percent ash in the formed pellets was 203/1962×100=10.4%ash It is noted that the lime Ca(OH)2) starts to convert to CaO at 450C. Each of the below samples had different levels of slaking and grind.As noted from the chart below, grind 2 was not as fine as grind 1. Thereaction of CaO with SO2 may be dependent on the fineness of the coke.Further, in some examples, the combination with high surface area lime(slake 3) provides a high degree of SO2 capture.

Est. SO2 % of Sample Slake Grind Ash + in ash* Capture Orig.** 1 2 115.9 5.6 5.6 80 2 2 Not 13.7 3.7 3.7 53 ground 3 3 1 16.8 6.4 6.4 91 4 42 15.4 5.4 5.4 77 5 3 2 14.75 4.6 4.6 66 *Ash in pellet mix 10.4%**Sulfur calculation - 1249 g coke × 5.5% = 69 g/1962 × 100 = 3.5% S =7.0% SO2 in pellet mix (dry basis)

Determination of the percent CAO added to the composition may be varieddepending on use. In one non-limiting example, 1300 g of pet coke wascontained in the pellet batch of 2000 g. The quantity of sulfur was 1300g×5.5% S=71.5 g of sulfur. One gram of sulfur=2 g SO2 where the reactionof SO2+CAO is equal to CASO3 such that 1.32 g SO2 is neutralized by 12 gCAO. With the 143 g sulfur in the pellet mix, 264 g CA(OH)2 (lime)−74MW−1.32 g lime yields 1 g CAO. The 264 g lime added yields 200 gCAO.

Of the 143 g SO2 in the 2000 g pellet mix, at 1.14 g SO2 to 1.0 g CAO,125 g were used to neutralize. In another example, 200 g CAO or 185% CAOused based on 100% CAO utilization of the CAO resulting in 60 to 80%efficiency. In one example, with calcium acetate and calcium magnesiumacetate the % CAO was 129% and 90% of required amount to neutralize the143 g sulfur in the pellets.

It is noted that in prior FGD methods (flue gas desulfurization), the %S capture is generally in the range of 60% to 80%. The disclosed pellettechnology compares favorably with the FGD methods with the Ca/S of2.0/1.0, however it should be appreciated that the ratio may be evenmore favorable with the disclosed pellets and such range is not intendedas a limitation. Further, in some examples, a 70% to 80% S capture at aCa/S of 1.7/1.0 was found. The lower Ca/S may be due to lime selection.It is noted that the stoichiometric Ca/S ration is 1.25/1.0.

As a non-limiting example of the calculated BTU/lb and lbs SO2/mm BTU inpellet formulation, total BTU per lb of pellet may be retained in thepellet formulation. For example, 1300 lb coke×15,415=20,039,500BTU/2000=10,019 lb. With 400 lb WF×8900=3,560,000 BTU/2000 lb=1780/lb.Total BTU per lb of pellet 11,7999. With lab analysis, an average BTUover a series of samples was 13456. The lbs SO2/mm BTU similarlycalculated with 1300 lb×5.5%=71.5 lbs sulfur equaling 143 lbs SO2.143/2000=0.0715 SO2 lb pellet×1000000/13456=5.3 lbs SO2/mm BTU. With theformulation of 0.0715×1000000/11799=6.1 lbs SO2/mm BTU. As a furtherexample, some samples yield less lbs SO2/MM BTU. The average ratio of %S/lbs SO2 per pellet formation was 1.48. An example, non-limiting ratiorange may extend from 1.37-1.50.

As further non-limiting examples to illustrate aspects of the invention,we note that in one example, a 2000 g batch of coke pellet mix wasconverted to a dry basis of 1893 g of coke pellet mix. The batchincluded 264 g of lime (Ca(OH)2. In this example, the batch was 76% CaO.It is noted that the lime converts to CaO at 450 C. The amount of CaO inthe example, including using 76% CaO in lime would be 201 gCaO/1893 orapproximately 0.106 g CaO/lb pellet mix (dry basis). As such, therewould be in this non-limiting example 10.6 lbs CaO per 100 lbs pelletfor approximately 10.6% ash. Another 0.2% ash from coke and wood fiberand the ash may be in the range of 10.8%.

In some examples, the ash was higher than 10.8%. The average for sampleswas approximately 15% ash. As another illustrative example, in 10.8 lbsash/100 lb with analysis at 15 lb, a gain of 4.2 lb was observed. 3.44lbs SO2 or 1.72 lbs sulfur was further observed. Starting with 3.6 lbsulfur/100 lb and removal of five pellets (48% of the sulfur) resultedin a fuel pellet with 1.88% average sulfur content.

Further, on individual pellet mixes the ash increased by 6 lb/100 lb(16.8−10.8) resulting in a pellet of 1.05% sulfur. Using the samecalculation as above, of the 3.6% in the pellet mix, there was a removalof 71% of the sulfur. The increase in ash would be higher at 900 C to1000 C.

As a further example formulation to produce a fuel briquette of lessthat 2% sulfur from the 5.5% sulfur coke a 100 lbs mix may include 65lbs coke, 30 lbs wood fiber and 5 lb hydrated lime producing a briquetteof 11,000 BTU/lb, 1.5 to 2.0% sulfur and 8% ash. The binder maycontribute a minimal level of sulfur but not enough to exceed the 2%level.

Turning now to another example, FIG. 3 provides an illustration ofcomponents for a petroleum coke-based fuel 300. Fuel 300 comprisespetroleum coke 302, a biomass constituent 304, an alkali constituent306, and iron oxide catalyst 308. Additional additives may be includedin fuel 100 without departing from the scope of the disclosure. Further,the description above in regards to petroleum coke-based fuel 100applies to the coke-based fuel 300 described here.

As described above, petroleum coke 302 is a byproduct/waste product ofcrude oil refining comprising a high carbon and sulfur content. Whilethe high carbon content of petroleum coke 102 may be desirable for itsenergy content, the sulfur content may lead to excessive SO2 emissions.Thus, the petroleum coke, although having a substantial energy densityin regards to use as a fuel, is considered a waste product due to thelevel of sulfur and the resulting SO2 emissions when burned.

In the present disclosure, petroleum coke may be combined with a biomassconstituent and an alkali constituent. In one example, alkaliconstituent 306 may comprise one or more compounds selected to capturethe SO2 produced during combustion of fuel 300. For example, alkaliconstituent 306 may be selected at least in part based on its surfacearea, as increased surface area may increase the amount of SO2 capturedby alkali constituent 106. In some embodiments, alkali constituent 306may be further processed (e.g., by grinding) to increase surface area.

Alkali constituents 306, also be referred to as an SO2 sorbent, maycomprise, for example, lime and calcium acetates. In some embodiments,alkali constituents 306 may be further processed to augment performance.

Further combined, in some examples, with the coke and the alkaliconstituent, is biomass constituent 304. Biomass constituent 304 mayprovide volatiles not present or are deficient in petroleum coke 302.Such volatiles may be selected as to increase the combustibility of thepetroleum coke 302. Biomass constituent 304 may comprise, for example,wood waste which, like petroleum coke 302, may be a byproduct/wasteproduct of one or more industrial processes.

In addition, the fuel pellet may include iron oxide catalyst, in theform of Fe₂O₃. In some examples, the iron oxide may be 2 to 4% by weightof the composition. The Fe₂O₃ may be added to catalyze the reaction ofCaO and SO2. In some examples, the addition of Fe₂O₃ may increase thecapture of SO2 by 25 to 35% in comparison to a fuel pellet without theaddition of iron oxide.

It should be appreciated that although described in this example with aniron oxide catalyst, other suitable catalysts may be used withoutdeparting from the scope of the disclosure. Thus, a catalyst thatcatalyzes the reaction of CaO and SO2 may be included in the pellet, incombination with the iron oxide catalyst or as a standalone catalyst.

As a non-limiting example, a high sulfur fuel pellet with reduced SO2emissions may include a combination of high sulfur petroleum coke, abiomass constituent, an alkali constituent and iron oxide catalyst. Asan example, a pellet with high sulfur petroleum coke, a biomassconstituent (such as wood chips), and an alkali constituent was shown tohave a 75.4% capture of SO2. With the addition of the iron oxidecatalyst, a pellet was tested to show a 95.3% and 94.4% capture. Therange of capture with the iron oxide catalyst is between 75% and 95%.

Below is a chart showing a comparison between two pellets. It is notedthat pellet #1, included petroleum coke 130 gm, wood fiber 40 gm andlime 22 gm and a binder. Pellet #2, illustrated in the chart below,included petroleum coke 130 gm, wood fiber 40 gm, lime 22 gm, Fe₂O₃ 2.6gm and a binder.

Pellet #2 Pellet #1 (with Iron Oxide catalyst) Sulfur in pellet  3.57% 3.35% Ash 14.84% 15.62% SO3 in ash 45.38% 50.61% S in ash 18.15% 20.24%gm S in ash 2.69  3.16  Percent SO2 capture  75.3%  94.4%

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and subcombinations of the various elements, features,functions and/or properties disclosed herein. Similarly, where theclaims recite “a” or “a first” element or the equivalent thereof, suchclaims should be understood to include incorporation of one or more suchelements, neither requiring, nor excluding, two or more such elements.

Inventions embodied in various combinations and subcombinations offeatures, functions, elements, and/or properties may be claimed in arelated application. Such claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower or equal in scope to any original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

1. A fuel comprising: petroleum coke, having a sulfur content up to5.5%; a biomass constituent; an alkali constituent adapted to captureSO2 emissions by reacting with sulfur of the petroleum coke upon burn ofthe fuel; and an iron oxide catalyst reducing SO2 emissions to less than10 percent; wherein the petroleum coke, the biomass constituent, thealkali constituent, and the iron oxide catalyst are combined to form afuel with decreased SO2 emissions at temperatures at or above 750 C. 2.The fuel of claim 1, wherein the fuel is in the form of one or more of abriquette, powder, bead, and various agglomerates.
 3. The fuel of claim1, wherein the alkali constituent is one of limestone, lime or sodiumbase alkali.
 4. The fuel of claim 3, wherein the alkali constituentcomprising lime is slaked.
 5. The fuel of claim 1, further comprisingone or more surfactants incorporated in the alkali constituent.
 6. Thefuel of claim 1 wherein the biomass constituent is wood waste.
 7. Thefuel of claim 1, wherein the biomass constituent includes a volatile toincrease combustibility of the petroleum coke.
 8. The fuel of claim 1,wherein the alkali constituent is processed to increase surface area ofthe alkali constituent, wherein processing includes grinding the alkaliconstituent, and wherein the increased surface area captures anincreased amount of SO2.
 9. A fuel comprising: petroleum coke, having asulfur content up to 5.5%; a biomass constituent to provide volatiles;an SO2 sorbent to capture SO2 emissions upon burn of the fuel; and Fe₂O₃as a catalyst reducing SO2 emissions in comparison to the fuel withoutaddition of Fe₂O₃; wherein the petroleum coke, the biomass constituent,the SO2 sorbent, and the Fe₂O₃ are combined to form a fuel withmaximized BTU value and reduced SO2 emissions at temperatures at orabove 750 C.
 10. The fuel of claim 9, wherein the SO2 sorbent isCa(OH)2.
 11. The fuel of claim 9, wherein the biomass constituent is inthe range of 10 to 50 percent by weight of the fuel.
 12. The fuel ofclaim 9, wherein the SO2 sorbent is in the range of 1 to 30 percent byweight of the fuel.
 13. The fuel of claim 9, wherein the petroleum cokeis in the range of 50 to 90 percent by weight of the fuel.
 14. The fuelof claim 9, wherein the fuel is in the form of one or more of abriquette, powder, bead, and various agglomerates.
 15. The fuel of claim9, where the Fe₂O₃ is in the range of 2 to 4 percent by weight of thefuel.
 16. The fuel of claim 9, wherein the Fe₂O₃ catalyzes a reactionbetween CaO and SO2.
 17. A fuel comprising: petroleum coke in the rangeof 50 to 90 percent by weight of the fuel; wood waste in the range of 10to 50 percent by weight of the fuel; Ca(OH)2 in the range of 1 to 30percent by weight of the fuel; and Fe₂O₃ in the range of 2 to 4 percentby weight of the fuel.
 18. The fuel of claim 17, wherein the petroleumcoke, the wood waste, the Ca(OH)2, and the Fe₂O₃ are combined to form afuel with decreased SO2 emissions at temperatures at or above 750 C. 19.The fuel of claim 17, wherein the Fe₂O₃ catalyzes a reaction between CaOand SO2, and Ca(OH)2 is a sorbent to capture SO2 emissions.
 20. The fuelof claim 17, wherein the fuel is in the form of one or more of abriquette, powder, bead, and various agglomerates.